There is currently no effective systems that simultaneous monitor workers on foot who work around plant and machinery both above and below ground. There is no way of alerting workers of a potential danger operating plant and machinery above and/below them or while working in close proximity around the plant and machinery. While there are GPS systems for above ground monitoring, they become useless in a tunnel below ground. On the other hand radio frequency identification devices can be used below ground but are inherently short range devices which require multiple nodes or beacons to activate associated transponders. There is presently no known system which allows the monitoring of a worker as he/she moves above ground to below or underground. In addition, plant and machinery operators do not have a way of monitoring workers on foot or to easily view and locate the workers who are not directly in their line of sight, for example even with the use of mirrors on heavy machinery, it still does not enable the operator to sight all areas of the plant even if they are working on the same level. The problem becomes more acute in below ground operations such as in underground mining or tunneling projects where workers are unsighted behind corners and tunnel walls.
While there may be the use of high visibility personal protection equipment, such as reflective apparel, flashing lights, audible warning alarms and/or safety spotters with radio communication, almost all of these systems require a direct line of sight or transmission to be effective. Audible warning horns or buzzers are also not always activated and can be muffled by workers wearing hearing protection. Furthermore, the direction of travel of moving vehicles or plant such as when reversing can affect the audible warning device. In the case of using human spotters, they also have to be in a direct fine of sight to be effective and may be subject to factors such as human error and in cases where spotter crew may not always be present. Furthermore, the spotters' radios can be muffled by hearing protection and are also of limited use in certain situations.
It is therefore an object of the invention to identify and seamlessly track the positions of workers whether they are working above or below ground level and when moving between the levels. It is a further object of the invention to seek to prevent serious injury or death to workers while interacting with plant and heavy machinery in use with a visual monitoring system that operates both above and below ground level in a seamless manner.